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Biomedical subjects

F Mizuno

Publications and source records attributed to F Mizuno.

At least 55 records · Page 3Linked to original sources
PubMed1985

Purification and preliminary characterization of exo-beta-D-fructosidase in Streptococcus salivarius KTA-19.

Streptococcus salivarius fructosidase (beta-D-fructan fructohydrolase, EC 3.2.1.80) was purified to homogeneity. The molecular weight of the fructosidase was estimated to be 83,000 to 85,000 by gel filtration and by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The pH optimum of the enzyme was 7.0, and the isoelectric point was pH 4.7. The purified enzyme preparation hydrolyzed levan, inulin, and several 2-beta-linkage-containing oligosaccharides such as sucrose and raffinose, but not melezitose, dextran, and pseudonigeran. The fructosidase was inhibited by Fe3+, Cu2+, Hg2+, and Ag+, but not by Ca2+, Co2+, Mg2+, and Zn2+, at a concentration of 10(-3) M. Mn2+ was particularly effective in stimulating activity at the same concentration. The presence of either EDTA or KCN also increased fructosidase activity by 20 to 30%. The enzyme was susceptible to sulfhydryl reagents since p-chloromercuribenzoate (10(-7) M) produced 63% inhibition of the activity. However, this inhibition was overcome in the presence of cysteine. This enzyme acts as an exofructosidase since thin-layer chromatographic analysis revealed that D-fructose was formed from levan or inulin by the action of the enzyme.

Cations↗
PubMed1985

Globoside and Forssman synthases in human lymphocytes exposed to Epstein-Barr virus and mitogens.

The activities of two glycolipid synthetases, globoside synthase or UDP-N-acetylgalactosamine-trihexosylceramide beta-N-acetylgalactosaminyltransferase (beta-GalNAc transferase; EC 2.4.1.79) and Forssman synthase or UDP-N-acetylgalactosamine-globoside-alpha-N-acetylgalactosaminyltransfer ase (alpha-GalNAc transferase; EC 2.4.1.88), were assayed in various human lymphoblastic cell lines. The activity of beta-GalNAc transferase was much higher than that of alpha-GalNAc transferase except in Molt 3 and Molt 4 lines, which were derived from T-cells. In cultivated human peripheral lymphocytes concanavalin A (Con A), lipopolysaccharide (LPS), and Epstein-Barr virus (EBV) stimulated the activities of alpha- and beta-GalNAc transferases in addition to having their known stimulative effect on thymidine incorporation. Characteristic differences between alpha- and beta-GalNAc transferases were noted in the responses to the above mitogens, but activities of both enzymes were greatly increased by exposure of the lymphocytes to EBV. Treatment of lymphocytes with either dactinomycin (actinomycin D) or cycloheximide 24 hours after the addition of Con A, LPS, or EBV decreased the activities of the transferases. This observation suggests that stimulation of alpha- and beta-GalNAc transferases requires transcriptional and translational processes.

Cell Line↗
PubMed1984

Interferon production by Epstein-Barr virus in human mononuclear leukocytes.

Interferon (IFN) production following exposure to Epstein-Barr virus (EBV) was studied in primary human mononuclear leukocytes. When the leukocytes were exposed to EBV (strain B95-8 or P3HR-1) the IFN level reached a maximum 24 h after exposure to the virus, and a gradual decrease followed. A linear relationship was obtained between the input dose of EBV and the IFN titre. The IFN inducibility of leukocytes did not correlate with the EBV infectibility. IFN was also induced by u.v.-inactivated EBV and heat-inactivated EBV, but not by neutralized virus. IFN inducibility varied among adult donors, but there was no significant difference between EBV-seropositive and -seronegative groups. The response of cord blood leukocytes, however, was lower than that of the cells from adults. The activity of all IFN samples in this study was stable to acid and heat and exclusively neutralized by anti-human IFN-alpha. B cells, T cells and NK cells all produced IFN in response to EBV, but monocytes did not.

Adult↗
PubMed1983

Chinese and African Euphorbiaceae plant extracts: markedly enhancing effect on Epstein-Barr virus-induced transformation.

Chinese and African Euphorbiaceae plant extracts were shown to have a markedly enhancing effect on Epstein-Barr virus (EBV)-induced transformation of human lymphocytes. When 5 X 10(5) cord blood lymphocytes were seeded into the semisolid agar medium immediately after EBV exposure, 3-10 times more colonies developed in the presence of the plant extracts at their optimal doses. When a smaller number of 5 X 10(4) cells were seeded, transformed colonies were also observed in the presence of the plant extracts but not in their absence. All of the colonies picked up from the agar medium were EBV-determined nuclear antigen (EBNA)-positive and showed the typical blastoid morphology. There were no colonies detected in the EBV-uninfected cultures with the extracts, indicating that the virus was required for the promotion by these plant extracts of this lymphocyte transformation. Euphorbiaceae plants are known to be employed as local herbal drugs in southern China and tropical Africa, and the possible role as a co-factor of the plant extracts in the development of nasopharyngeal carcinoma (NPC) and African Burkitt's lymphoma (BL) is discussed.

Africa↗
PubMed1983

Isolation and properties of levanase from Streptococcus salivarius KTA-19.

Fructan-hydrolyzing enzyme from Streptococcus salivarius KTA-19 isolated from human dental plaque was investigated. The enzyme was purified by ammonium sulfate precipitation, acetone fractionation, and column chromatography on Bio-Gel and DEAE-cellulose. The purified enzyme showed a single band on sodium dodecyl sulfate-polyacrylamide gel electrophoresis and isoelectric focusing. Its molecular weight was 100,000 as determined by sodium dodecyl sulfate polyacrylamide gel electrophoresis. The enzyme exhibited an optimum pH of 6.5 and decreased its activity from pH 6.0 and especially below pH 5.5. The optimum temperature was 40 to 50 degrees C, and enzyme activity was reduced by 90% at 55 degrees C. Enzyme activity was markedly inhibited by Hg2+, Ag+, Cu2+, and p-chloromercuribenzoate at a concentration of 10(-3) M, but not by other metal ions or chemical effectors. Fructose was the only by-product of the enzyme action on levan. These results indicated that the levanase of S. salivarius KTA-19 is an exo-beta-(2,6)-fructofuranosidase.

Bacterial Proteins↗
PubMed1980

Glycosaminoglycan content and synthesis in gastric carcinoma.

The glycosaminoglycan (GAG) content of stomach carcinoma tissue was compared with that of non-neoplastic mucosa. GAG synthesis was also studied, by an analysis of 35S-labelled material after incubation of tissue segments in medium containing 35SO4. No significant difference was found between the amount of GAG and its components in the medullary carcinoma tissue and in non-neoplastic mucosa, but GAG synthesis of the carcinoma tissue was at a much higher rate than that of the non-neoplastic mucosa. In the autoradiograph, high 35S uptake in the carcinoma cells was observed. The GAG content of the scirrhous-carcinoma tissue was about twice that of medullary carcinoma.

Chondroitin Sulfates↗
PubMed1980

Immunologic cytotoxicity against autologous human lymphocytes transformed or infected by Epstein-Bar virus: role of antibody-dependent cellular cytotoxicity in health individuals.

Immunologic cytotoxicity against lymphocytes transformed or infected by Epstein-Barr virus (EBV) was mainly studied in an autologous in vitro system by 51Cr release assay and EBV-determined nuclear antigen (EBNA)-specific trypan blue exclusion method. When the cells of newly established EBV-transformed or spontaneously transformed lines were incubated with unfractionated autologous healthy donor lymphocytes or T-cell-depleted lymphocytes in the presence of EBV-positive autologous or allogeneic serum, the transformed cells were killed with high frequency. Exposure to lymphocytes alone or to EBV-positive serum alone was not effective. The cytotoxic reaction was directed against cells positive for EBV-induced membrane antigens (MA) but not against MA-negative transformed cells. A very small fraction (1 of 200) of healthy donor lymp]hocytes exposed to EBV converted into EBNA-positive and MA-positive cells, and these were also killed by the remaining autologous lymphocytes in the presence of EBV-positive serum. These results indicated that the present cytotoxic reaction represents antibody-dependent cellular cytotoxicity (ADCC), and this particular mechanism probably plays an important role in the immunologic surveillance in the protection against EBV-induced oncogenesis in seropositive individuals. Such ADCC, however, does not seem to function effectively in patients with systemic lupus erythematosus.

Antibodies, Viral↗